![]() Potassium is an essential nutrient for plants and animals. It is found in mineral waters, brines, and salt deposits. ![]() It is the seventh most abundant element in the earth's crust and the sixth most abundant of the elements in solution in the oceans. KCl), feldspar, mica, and other minerals.Potassium does not occur uncombined in nature but is found widely distributed in sylvite (KCl), carnallite (MgCl 2 Substances containing potassium impart a purple color to a flame. With sodium the metal forms alloys that are liquid at room temperature these alloys are sometimes used in chemical reactions. Potassium permanganate, KMnO 4, a purple-black, crystalline compound that forms deep purple, aqueous solutions, is used in the chemical laboratory as a powerful oxidizing agent and in medicine as an antiseptic and disinfectant. Potassium aluminum sulfate, KAl(SO 4) 2♱2H 2O, is a compound used in tanning, in water purification, and in baking powder usually called alum, it is also called potash alum to distinguish it from other alkali aluminum sulfates. ![]() Potassium has several useful tartaric acid salts, e.g., Rochelle salt (sodium potassium tartrate), tartar (argol) and cream of tartar (potassium hydrogen tartrate), and tartar emetic (potassium antimony tartrate). The metasilicate, K 2SiO 3, is used in water glass. Javelle water contains potassium hypochlorite, KClO, a compound found only in solution. Other commercially useful compounds include the bromide, KBr, the cyanide, KCN, the chromate, K 2CrO 4, the dichromate, K 2Cr 2O 7, and the iodide, KI. The nitrate, saltpeter (or niter), KNO 3, is used in matches and explosives. The hydroxide, or caustic potash, KOH, is used in soaps. The chlorate, KClO 3, and perchlorate, KClO 4, are used in explosives and fireworks. The chloride, KCl, is used in fertilizers and in the production of other potassium compounds. Potassium carbonate, or potash, K 2CO 3, is used principally in soap and glass manufacture. Nonetheless, potassium compounds are widely used in industry, although they are usually more expensive than the similar sodium compound. The metal has limited use since it so closely resembles sodium, which is readily available at lower cost. ![]() It combines directly with the halogens, sulfur, and other nonmetallic elements (except nitrogen). It reacts violently with water to form potassium hydroxide, KOH, releasing hydrogen, which usually ignites. It combines so readily with oxygen that it is usually stored submerged in kerosene or some other hydrocarbon, out of contact with air. It is extremely reactive, more so than sodium. Physically and chemically it resembles the other alkali metals in Group 1 of the periodic table. Potassium pətăsˈēəm, a metallic chemical element symbol K at. ![]()
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